Jökull - 01.12.1990, Blaðsíða 13

Figure 4. A synthesis of the characterizing criteria for the diamictite facies assemblages identified in the upper
Borgarfjörðurand the Hvalfjörður areas. G= glass, M= minerals, R= rockfragments. Shaded areas in clast fabric
projections indicate maximum intensity of clast long axes orientation. NRM= natural remanent magnetization.
AMS= anisotropy of magnetic susceptibility, kmax,int,min= magnetic susceptibility, max-, int.-, min- directions.
Einfölduð samantekt á helstu einkennum setlaga úr illa aðgreindu efni í ofanverðum Borgarfirði og Hvalfirði.
G=gler, M=steindir, R=bergbrot. Skyggð svœði í veftu-diagrömmum gefa til kynna algengustu stefnu langása
hnullunga í setinu. NRM= stefna varanlegrar segulmögnunar. AMS= mismunastefnur segulviðtaks, kmax, int,
min= segulviðtak, stœrsta, meðal, minnsta gildi segulviðtaks.
to the limited outcrops of underlying basalt, and to
the indurated nature of the diamictites which impairs
detailed study of pebble striations. The degree of sed-
IIT|ent lithification also made it impossible to perform
a systematic study of boulder shape, but whenever
Possible, pebble and boulder roundness was assessed
visually in the field. However, the use of the multiple
criterion mentioned above, recognition of the strati-
graphic framework and the facies sequences, which
are attributed to a particular environment, allow the
origin of the sediments to be inferred (Fig. 4). A syn-
thesis of these various types of criteria used in this
study to differentiate the diamictites indicates that a
combination of volcanic and glacial activity promoted
the deposition of late Pliocene sediments in the up-
per Borgarfjörður and Hvalfjörður areas (Fig. 4 and
Fig. 5).
JÖKULL, No. 40, 1990 11